# Documentation for sd (stats) + suggestion

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## Documentation for sd (stats) + suggestion

 I cannot file suggestions on bugzilla, so writing here. As far as I can tell, the manual help page for ``sd`` ?sd does not explicitly mention that the formula for the standard deviation is the so-called "Bessel-corrected" formula (divide by n-1 rather than n). I suggest it should be stated near the top. I would also suggest (feature request!) that either  - a population standard deviation formula, e.g. ``sdp`` or ``sd.p`` be made available (that would be my preference) or  - the current ``sd`` be extended to accept a ``population=FALSE`` or ``sample=TRUE`` argument. Same for the variance. Excel, Calc, etc. offer these. Motivation: I encourage my students to use R rather than Python (which has picked up big time in recent years) on the grounds that it is easier to get started with and is specialized in statistics. But then there is no "population" formula for the standard deviation. And ``mode`` is not the mode they expect... (btw I suggest adding a ``modes`` function to the core)  All things a beginner will look for in a stats software. Thanks for listening. And thanks for the great work!         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
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## Re: Documentation for sd (stats) + suggestion

 > As far as I can tell, the manual help page for ``sd`` > > ?sd > > does not explicitly mention that the formula for the standard deviation is > the so-called "Bessel-corrected" formula (divide by n-1 rather than n). See Details, where it says "Details:      Like 'var' this uses denominator n - 1. " ******************************************************************* This email and any attachments are confidential. Any use...{{dropped:8}} ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
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## Re: Documentation for sd (stats) + suggestion

 Good day, It is implemented by the CRAN package multicon. The function is named popsd. But it does seem like something R should provide without creating a package dependency. -------------------------------------- Dario Strbenac University of Sydney Camperdown NSW 2050 Australia ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel